It was proposed over the course of this year to further develop and refine the technology necessary to replace the natural heart with a pneumatically powered artificial heart. We proposed to demonstrate the integrity of the Starling's response control mechnism in the pneumatic artificial heart by long-term chronic experiments, where calves continue to grow at a normal growth rate and exercise on a treadmill, and we hope to repeat an experiment with a calf surviving one-half year with a total artificial heart. We will test the efficacy of parameters including blood chemistries, hematological factors and serum enzymes. Further evaluation of the integrity of the artificial heart will be examined during autopsy of the various organ systems of the calf as well as a study of the artificial heart itself as it appears at autopsy.